Coating improves solar panel efficiency by 30%

[n2doc]

By Julie Steenhuysen

CHICAGO (Reuters) - A new type of reflective coating can make solar panels far more efficient, soaking up nearly all available sunlight from nearly any angle, U.S. researchers said on Monday.

Current solar panels -- which convert energy from the sun into electricity -- absorb only about two-thirds of available sunlight.

But surfaces treated with a coating developed at Rensselaer Polytechnic Institute in Troy, New York, can harvest 96.2 percent of sunlight.

"That is a tremendous savings," Rensselaer's Shawn-Yu Lin, whose study appears in the journal Optics Letters, said in a telephone interview.

Lin said the technology addresses two main problems in current solar cells. It captures more colors of solar spectrum and it captures light from all angles.

"If you look at a solar panel, it looks a bit bluish," Lin said. That is "telling you not all of the blue color is being absorbed. It should look totally dark."

The other problem is that solar panels work best when sun shines directly on them. To solve this, large solar arrays mechanically shift position throughout the day -- much like sunbathers on a beach.

Lin and colleagues think they have found a better solution.

Their coating is made up of seven layers of porous material stacked in such a way that each enhances the antireflective properties of the layer below.

Together they act as a buffer zone, trapping light from all angles. "Your efficiency increases by 30 percent," Lin said.

He thinks the material could be applied to all types of solar cells.

"It's not going to require many added instruments to adopt this technology," he said.

(Reporting by Julie Steenhuysen, Editing by Anthony Boadle)
http://www.reuters.com/article/environmentNews/idUSTRE4A26XF20081103?rpc=64

[phantom power]

1. methinks somebody used "reflective" incorrectly...

but interesting idea. Sounds kind of like a metamaterial.

[The2ndWheel]

2. "soaking up nearly all available sunlight from nearly any angle"

Doesn't sound like conservation. Sounds like massive consumption.

Sucks for the rest of life I guess, except whatever we find useful. Privatize the profits, socialize the costs.

[kestrel91316]

3. We have no shortage of sunlight. And no plant life is living on rooftops

underneath solar panels to suffer from the loss of light.

You prefer we NOT improve solar panel efficiency??? Perhaps the solution is suicide of the entire human race. You could set an example and go first. :sarcasm:

[The2ndWheel]

13. What would stop us from attempting to soak up all of the available sunlight for our use?

Because there is more energy available than we need? When have we given up energy? If it's available for our use, we will use it. We're not going to invest all that time and money into improving our ability to extract and harness more energy from the environment so that we don't control it.

[phantom power]

14. I'm not sure I follow you...

are you worried we're going to blanket planet earth in PV panels, intercepting all the photons?

[The2ndWheel]

15. Well, we drill every oil deposit(or at least want to)

We fish anywhere we can. We grow food anywhere it's possible, and even where it isn't without massive amounts of fertilizer. You'll find human beings in almost every inch of the globe. We'll change the climate, with A/C or heating, so that it doesn't matter where we are.

So yes, if we can, we'll blanket the planet in PV panels. Or we'll construct an orbit of PV panels around the planet, catching the solar rays before they hit the earth. Tough to predict exactly, but I doubt we stop at rooftops.

We'll have consequences no matter what we do. Hunting with sharp sticks impacted the environment. Governments and corporations on a planetary scale investing who knows how much time and money into improving our ability to extract and harness almost all of the available sunlight from any angle to power a global civilization with unlimited energy where billions of people and all their needs and wants exist in a growing economy while living in the same space as countless other forms of life...I'm just not sure how that decreases our impact on the environment.

[phantom power]

16. I see. Two topics we discuss pretty frequently here.

1) Human civilization, at least in its current incarnation, has an insatiable character about it.

2) Industrial economies always involve significant environmental impact. It becomes a choice as to which kinds of impact to choose.

It's (1) and (2) that leads GG to advocate ideas like this.

[phantom power]

4. I wonder if it would be even more effective for solar thermal.

Thermal can get more mileage out of all frequencies, unlike PV.

[skids]

6. Probably not...

thermal already employs anti-reflective coatings and already absorbs nearly the full spectrum -- which is why you get so much more watts thermal per square foot than you get watts electrical from a PV panel.

Though I have to admit, if the nanosolar stuff kicks in fast enough to actually bring prices down to the $1/watt target, then a solar PV array in combination with a heat pump might manage to take the payback-time crown away from solar hot water/space heating.

[phantom power]

7. But... if this coating brings in light from 0 - 60 degrees...

wouldn't that also be a win for fixed-position thermal panels?

[skids]

8. The angle of incidence problem is specific to Si cells not black bodies...

...I mean other than the obvious projected surface area. What is why fixed thin film panels have a different power curve.

[phantom power]

9. Hmm. Doesn't alter projected surface area, does it.

[skids]

10. Nope only tracking can do that....

...and then as far as rooftop real estate you have to have spacing between the cells to have the same area at all daytimes. IIRC the trough-PV-strip tracking systems space a little tightly so there's not too much waste in unused spacing, so there's still a bit of taper-off from shadows.

Which is why if you ever build a house, proper orientation of the roof for your longitude and latitude even if you're not installing cells immediately should be a consideration.

[phantom power]

11. But wait, are you saying that in the case of PV...

power falls off faster than the decline due to projected area?

[skids]

12. For some cell technologies, yes.

If you are buying cells ask to see the "IAM curve".

[Finishline42]

17. Combined PV and Solar Thermal panel

Here's a panel that combines both.

"Australian, American and Chinese researchers are exploring the possibility of combing solar thermal and PV on rooftops, a move that could potentially cut the cost of solar energy."

"Scientists from the Australian National University (ANU), Tianjin University in China and Chromasun, a Silicon Valley company with strong Australian connections, will join forces to create roof-mounted solar trough concentrator systems that they believe will be more cost-effective and efficient than previous models. The aim is to make the systems ideal for take-up in emerging economies like China and by budget and environmentally conscious consumers in developed nations."

http://www.renewableenergyworld.com/rea/news/story?id=53981

[Grinchie]

18. Thats what I is thinking, Solar panels only use a narrow wavelength of light

Which allows them to convert 10% to 15% of Solar Energy into electricity.

Solar Cells are just another form of diode, and LED's can convert Light into electricty as well. Different material produce different colors emitted from an LED.

They have made huge breakthoughs recently with LED's consisting of almost every color, including White LED's, so it's only natural that they will come up with a broader wavelength capture for Photvoltaics.

Although I was a big supporter of NanoSolar, I am becoming worried that their amazing "Printed" solar panel is going to be suppressed, especially since the Carlyle Group just invested so heavily in them recently.

They initially claimed $1.00 a watt, but they decided to supply only Industrial scale utility companies, and not supply directly to consumer. It's becoming more and more disturbing to see them withholding this product from the market.

[kristopher]

5. Ref and abstract for original paper

Opt Lett. 2008 Nov 1;33 (21):2527-9 18978909 (P,S,G,E,B)

Realization of a near-perfect antireflection coating for silicon solar energy utilization.

Mei-Ling Kuo, David J Poxson, Yong Sung Kim, Frank W Mont, Jong Kyu Kim, E Fred Schubert, Shawn-Yu Lin

To harness the full spectrum of solar energy, Fresnel reflection at the surface of a solar cell must be eliminated over the entire solar spectrum and at all angles. Here, we show that a multilayer nanostructure having a graded-index profile, as predicted by theory , can accomplish a near-perfect transmission of all-color of sunlight. An ultralow total reflectance of 1%-6% has been achieved over a broad spectrum, lambda=400to1600 nm, and a wide range of angles of incidence, theta=0 degrees -60 degrees . The measured angle- and wavelength-averaged total reflectance of 3.79% is the smallest ever reported in the literature, to our knowledge.

http://lib.bioinfo.pl/pmid:18978909